Sorbent extraction sorbents

Sorbent extraction Sorbent extraction makes use of the differential distribution of the dissolved compounds between the solid sorbent and water. The use of organic porous polymers is advantageous for the extraction of organic compounds from water because (1) the partition coefficients of compounds in a polymer-water system reach infinity if the correct polymer is selected for the types of contaminants present (2) adsorption of water itself on the polymer is minimal (3) the wettability of the polymer with water makes possible satisfactory transport of the substance toward the polymer surface and (4) the polymer is inert. 

Air Collect on solid sorbent extract with diethyl ether in hexane GC/FPD No data 72-105 EPA1980d... 

Although SPE can be done in a batch equilibration similar to that used in LLE, it is much more common to use a small tube (minicolumn) or cartridge packed with the solid particles. SPE is often referred to as LSE, bonded phase or sorbent extraction SPE is a refinement of open-column chromatography. The mechanisms of retention include reversed phase, normal phase, and ion exchange. 

High selectivity (i.e. the ability to separate analytes from matrix interferences) is one of the most powerful aspects of SPE. This highly selective nature of SPE is based on the extraction sorbent chemistry, on the great variety of possible sorbent/solvent combinations to effect highly selective extractions (more limited in LLE where immiscible liquids are needed) and on the choice of SPE operating modes. Consequently, SPE solves many of the most demanding sample preparation problems. 

N. Simpson and K.C. van Home (eds), Varian Sorbent Extraction Technology Elandbook, Varian Sample Preparation Products, Harbor City, CA (1993). 

M. Zief and R. Kiser, Sorbent Extraction for Sample Preparation, J.T. Baker, Phillipsburg, NJ (1988). 

K. C. van Horne, Sorbent Extraction Technology, Analytichem International, Harbor City, CA (1985). 

Flow-injection (FI) on-line analyte preconcentration and matrix removal techniques greatly enhance the performance of atomic spectrometry [348], By using USN with membrane desolvation (MDS) as the interface, FI sorbent extraction can be directly coupled with ICP-MS for the analysis of organic solutions [349]. 

Wachs, T. and Henion, J. 2003. A device for automated direct sampling and quantitation from solid-phase sorbent extraction cards by electrospray tandem mass spectrometry. Anal. Chem. 75 1769. 

In solid phase extraction, the liquid solution containing the analyte is passed through a cartridge containing a solid sorbent. The sorbent retains either the analyte or its matrix. If it is the analyte that is retained by the sorbent, the cartridge is first washed with a solvent that will sweep away interferences. The analyte is then eluted with a stronger solvent and collected. If it is the matrix that is retained by the sorbent, the analyte is eluted immediately and collected. 

Hennion MC, Coquart V. 1993. Comparison of reverse-phase extraction sorbents for the on-line trace enrichment of polar organic compounds in environmental aqueous samples. J Chromatogr 642 211-224... 

Several analytical methods for the determination of aldehydes in beer have been developed, and good results have been obtained using liquid-liquid extraction (2), distillation (3), or sorbent extraction (T). However, these methods are rather complicated and not highly selective. 

In 1985, Ruzicka and Hansen established the principles behind flow injection optosensing [13-15], which has subsequently been used for making reaction-rate measurements [16], pH measurements by means of immobilized indicators [17,18], enzyme assays [19], solid-phase analyte preconcentration by sorbent extraction [20] and even anion determinations by catalysed reduction of a solid phase [21] —all these applications are discussed in Chapters 3 and 4. Incorporation of a gas-diffusion membrane in this type of sensor results in substantially improved sensitivity (through preconcentration) and selectivity (through removal of non-volatile interferents). The first model sensor of this type was developed for the determination of ammonium [13] and later refined by Hansen et al. [22,23] for successful application to clinical samples. 

Andersson LI, Paprica A, Arvidsson T. A highly selective sohd phase extraction sorbent for pre-concentration of sameridine made by molecular imprinting. Chromatographia 1997 46 57-62. 

Vaananen, T., Kuronen, P., Pehu, E. (2000). Comparison of commercial solid-phase extraction sorbents for the sample preparation of potato glycoalkaloids. J. Chromatogr. A, 869, 301-305. 

J. T. Baker, Application Guide, Vols. 1 and 2, Philipsburg, NJ, USA (1984). Sorbent Extraction Technology Handbook, Analytichem International Inc., Harbor City, CA, USA (1985). 

In SPE, the extraction is carried out using a small column (syringe-type or cartridge) containing 0.1 to 1 g of sorbent. The sorbent is typically a modified silica gel or one of many copolymers. This chemical filter can only be used once. The low-cost SPE process, which can be readily automated, is generally more useful for hydrophobic or apolar compounds than it is for ionic substances. 

Procedures. Sorbent Conditioning. To facilitate partitioning of organics in aqueous solution onto hydrophobic nonpolar sorbents, the sorbents must first be conditioned with methanol to increase their wettability. This solvation of the solid phase is necessary to provide efficient and reproducible extractions. The conditioning process was carried out according to the instructions accompanying tbe extraction columns. 

Analytical Methods. All of the sorbent extracts were analyzed by using GC-MS. The solutions were chromatographed on a 30-m X 0.32-mm i.d. Supelcowax 10 capillary column with a film thickness of 1 /um (Supelco). The Supelcowax 10 is a Carbowax PEG 20 M bonded-phase capillary column. The instrument conditions were as follows injector, 250 °C separator oven, 250 °C column over initial, 40 °C programmed to 250 °C at 6 °C/min linear velocity of helium carrier gas, 35 cm/s at 40 °C column head pressure, 6 lb/in.2 mass range, 33-333 amu scanned in 1-s intervals. Two-microliter aliquots were injected in the split mode at a 10-to-l split ratio. A typical chromatogram appears in Figure 1. 

Miro, M. and Frenzel, W., A critical examination of sorbent extraction preconcentration with spectrophotometric sensing in flowing systems, Talanta, 64, 290-301, 2004. 

Egorov, O., Grate, J. W., and Ruzicka, J., Automation of radiochemical analysis by flow injection techniques Am-Pu separation using TRU-resin sorbent extraction column, J. Radioanal. Nucl. Chem., 234, 231-235, 1998. 

Grate, J. W. and Egorov, O., Investigation and optimization of on-column redox reactions in the sorbent extraction separation of americium and plutonium using flow injection analysis, Anal. Chem., 70, 3920-3929, 1998. 

Determinand Subcritical water extractant Sorbent trap Analytical finish Reference... 

Sorbent extraction Exclusion of salts Limited solubility of human matter, partly irreversible sorption... 

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